How do you win at pandemic 2

I have noticed that the best way to win is to remain undetected as long as possible, and then once the world starts to shut down, you upgrade the lethality.

So I sell my starting symptoms and build up tolerance to heat, cold, and moisture to level four, and getting drugs to level 2 or three depending on what type of disease you are (3 for virus, 2 for parasite).

Next get all of the transmission upgrades, starting with Airborne and Waterborne, then insect and rodent later.

About now, the entire world should be freaking out and shutting everything down. Then you start to pick symptoms that are funny! (and preferably deadly otherwise you are gonna be starring at a red globe for quite awhile...)